ANION-SELECTIVE POLYMERIC MEMBRANE ELECTRODES BASED ON METALLOCENES

Seven types of metallocenes (bis-cyclopentadienyl compounds) were used as anion ionophores for polymeric membrane electrodes and their anion selectivities were examined. The electrodes based on metallocenes exh ibited different selectivity behaviour compared with the electrode usi ng a classical anion exchanger such as tetraalkyl ammonium. The select ivity for tetraalkyl ammonium simply obeys the lipophilicity of anions , specifically, hafnocene dichloride exhibited a highly specific respo nse to anions that have pi-electrons such as the salicylate ion. This electrode demonstrated a Nernstian response to the salicylate anion ra nging from 1 X 10(-3) to 1 X 10(-1) M in a buffered solution (0.05 M T ris-H2SO4) adjusted to a pH of 7.4.